April 2019 Climate and Hydrology Summary

Tulsa: April 2019 was the 30th warmest (62.9°F, tied 2015; since 1905) and the 35th wettest (5.34"; since 1888) April on record. No snow fell in April.

Tulsa: Daily records set or tied this month include a record daily rainfall.

Tulsa: The 2018-19 cold season ranked as the 21st least snowy (since records began in 1900-01) with 2.9".

Fort Smith: April 2019 was the 39th warmest (63.3°F tied 1887; since 1883) and the 26th wettest (6.71", tied 1908; since 1883) April on record. No snow fell in April.

Fort Smith: No daily records were set or tied this month.

Fort Smith: The 2018-19 cold season ranked as the 26th least snowy (since records began in 1883-84) with 1" of snow (tied 1982-83).

Fayetteville: April 2019 was the 29th warmest (58.5°F; since 1950), the 25th wettest (5.11"; since 1950), and the 3rd snowiest (Trace, tied 15 other years; since 1950) April on record.

Fayetteville: Daily records set or tied this month include a record warm maximum temperature.

Fayetteville: The 2018-19 cold season ranked as the 16th least snowy (since records began in 1949-50) with 2" of snow (tied 1961-62, 1986-87).

McAlester: Daily records set or tied this month include a record warm maximum temperatures and a record warm mean temperature.

Using the radar-derived estimated observed precipitation from the RFCs, rainfall totals for April 2019 ranged from 3” to around 10” across eastern OK and northwest AR. The majority of this rainfall occurred with the April 30 heavy rain event. These rainfall totals correspond to 50%-90% of the normal April rainfall across a large portion of Osage, Pawnee, and eastern Kay Counties. A few smaller areas across northwest OK and west central AR received 90-110% of the normal April rainfall. Elsewhere, much of eastern OK and northwest AR received 110% to around 200% of the normal April.

Minor to moderate river flooding occurred this month along Polecat Creek near Sapulpa, Bird Creek near Sperry, Caney River near Collinsville, Verdigris River near Lenapah, Illinois River near Watts, Chewey, and Tahlequah, Poteau River near Poteau and Panama, Neosho River near Commerce, Spring River near Quapaw, and the Kiamichi River near Antlers.

A significant storm system brought tornadoes, flash flooding, and river flooding to eastern OK and northwest AR at the end of the month, with additional rain events mid- and late-month.

On April 30, 2019, 13 tornadoes (ranging from EF-0 to EF-2) occurred across eastern OK (see https://arcg.is/1X8eW1 for more information).

Showers and thunderstorms moved north out of TX and into southeast OK and west central AR during the morning of the 14th, as an upper-level low moved across northwest TX. This activity remained widespread as it spread northward through the afternoon hours. By evening, the upper low began to move into southeast OK, with the rainfall continuing along the northern periphery across northeast OK and northwest AR. As the low continued to move east into AR, the rain spread back into all of eastern OK and western AR on the back side through the overnight hours, and came to an end around sunrise on the 14th. Rainfall totals ranged from 1.5”-3” southeast of I-44, with significantly lesser amounts northwest of I-44. This rainfall caused the Poteau River near Panama to rise to flood stage.

Isolated thunderstorms affected southeast OK and west central AR during the afternoon and evening of the 17th. Then, by late evening, two different lines of thunderstorms moved out of central OK into eastern OK. The northern line, associated with a cold front, weakened as it moved across northeast OK and northwest AR. The southern line, associated with dry line convection, moved across southeast OK and west central AR, bringing more widespread rainfall through the overnight and early morning hours. Rainfall totals ranged from around 0.50” to around 2” in southeast OK and western AR. Further north, the rainfall totals were around 0.50” or less northwest of I-44. However, just northwest of the NWS Tulsa area, heavy rainfall of 1.5”-3” fell across southern KS and north central OK, with the upper portions of the Arkansas and Verdigris River basins.

The remnants of a mesoscale convective system (MCS) moved across northeast OK, northwest of I-44, during the mid-morning hours of the 23rd. This activity brought widespread 0.50”-1.5” of rainfall across the affected area, with a narrow band of 1.5”-2.5” of rain to northern Pawnee and the adjacent portion of Osage Counties. Isolated to scattered activity during the evening and overnight hours brought localized 0.50” to 1.5” of rain to portions of eastern OK.

Showers and thunderstorms moved north out of TX into southeast OK and west central AR during the evening of the 24th. This activity continued through the overnight hours and lingered until noon on the 25th, affecting southeast OK and western AR southeast of an Okmulgee-Bentonville line. Rainfall totals were primarily 0.50”-1” with a few isolated amounts around 1.5” in northern Le Flore County, which resulted in minor flooding on the Poteau River near Panama.

A line of showers and thunderstorms near a surface boundary moved across north central and northeast OK in the pre-dawn hours of the 30th. As this activity moved north into KS at mid-morning, another line of showers and thunderstorms from central OK spread northeast into northeast OK along the front as it slowly moved south. Additional thunderstorms developed near, as well as ahead of the front in the warm sector, during the afternoon. Several of these storms became severe, with moisture and shear parameters supportive of rotating supercells. 13 tornadoes (ranging from EF-0 to EF-2) occurred across eastern OK (see https://arcg.is/1X8eW1 for more information). On the synoptic scale, southwest deep-layer flow (parallel to the front) and a high precipitable water (near 2”) airmass supported repeated rounds of training thunderstorms, which resulted in heavy rain and flooding. By early evening, thunderstorms congealed into a line across northeast OK, spread east through the evening, and produced very heavy rainfall. Widespread showers and thunderstorms continued behind the leading line, covering all of eastern OK and northwest AR by late evening. As this area of rain pushed east of the region in the very early morning hours, yet another area of showers and thunderstorms developed over southeast OK and moved northeast, and a line of thunderstorms over central OK moved east as a squall line. All of this activity brought additional rainfall to a large portion of eastern OK and northwest AR. The rain finally came to an end by mid-morning on May 1. Most of eastern OK and northwest AR received 2”-3” of rain from this event, with higher totals of 4”-6.5” in portions of northeast OK and southeast OK. Widespread flash flooding occurred with this heavy rain, and one fatality (pending medical examiner’s report) occurred in Tulsa, OK when a motorist left the highway, drove into a swollen drainage ditch, and was washed downstream. The official observing site in Tulsa, OK recorded 3.15” of rain on April 30, most of which fell in a few hours, setting a new daily rainfall record for that day (previous record was 3.00” in 1970). Additionally, all of the water resulted in significant rises along area creeks and rivers, and minor to moderate river flooding along the Polecat Creek near Sapulpa, Bird Creek near Sperry, Caney River near Collinsville, Verdigris River near Lenapah, Illinois River near Watts, Chewey, and Tahlequah, Poteau River near Poteau and Panama, Neosho River near Commerce, Spring River near Quapaw, and the Kiamichi River near Antlers.

According to the Drought Monitor from April 30, 2019, no drought or abnormally dry conditions were present across eastern OK and northwest AR.

According to the Oklahoma Climatological Survey, April 2019 was the 24th wettest for northeast Oklahoma, the 29th wettest for east central Oklahoma, and the 24th wettest for southeast Oklahoma. Records go back to 1921. For the Year-to-Date period Jan. 1-Apr. 30, 2019, northeast Oklahoma ranked as the 17th wettest, east central Oklahoma was the 14th wettest, and southeast Oklahoma was the 37th wettest period. For the last 365 days (May 1, 2018-April 30, 2019), northeast Oklahoma was the 39th wettest, east central Oklahoma was the 18th wettest, and southeast Oklahoma was the 18th wettest.